DIY Doctor UK DIY Forums

Last year I bought ten 10mm thick glass panes to build a ‘glass box’ porch to fit into an ‘L’ shaped corner of my house. The seller (an experienced glass merchant about to retire) told me the 1.98 x 1.015m 'roof' panes would self support on the long dimension – that is with a shallow pitch and the top edge fixed using car windscreen bonding adhesive or suitable silicone … spanning 1.9m sloping down to the glass wall frame.

The glass 'wall' will sit on low block walls about one metre high with a top frame (acting as a wall plate) and door frame providing support for four 1.219 x 0.710m panes – one used for a sliding door.

Having checked an online Dow Corning structural glass guide for vertical silicone butt joint info, it seems normal practice to use laminated glass for an application like this. The panes are not marked to say they are safety glass. Alarm bells are ringing about breakage of such heavy glass then falling on someone below.

The aim is for minimal framing but I wonder if safety dictates using two strong, inverted ‘T’ metal section for butt joining/supporting the three glass ‘roof’ panes – with a wall support at one side and a strong frame on the other. That would still leave an unsupported span width of almost one metre.

I would rather not have to chicken out and use a light multi-wall polycarbonate sheet roof system. Any thoughts will be appreciated.

10mm plate glass is not suitable for roof installation and dangerous.
you can purchase a flat roof system designed for your needs from any double glazing company.Any you dont have to have polycarb you can have toughened glass instead.

welsh brickie wrote:10mm plate glass is not suitable for roof installation and dangerous.
you can purchase a flat roof system designed for your needs from any double glazing company.Any you dont have to have polycarb you can have toughened glass instead.

Many thanks Welsh Brickie for confirming the "dangerous" part ... I feared as much. I hoped to avoid the cost of toughened glass having forked out already. But better safe than sorry!

By "toughened" does that mean it doesn't have to be laminated or is lamin the best choice because it doesn't break into fragments?

Much obliged, DD

Toughened , glass is heated and cooled and the molicules are under tension but makes it very hard to break. Its a lot lighter and very strong. When its broken,it shatters into very small pieces.
Laminated is 2 pieces of glass with a plastic film, like clingfilm sandwiched together.This can be done many times and used as bullet proof glass,The problem with laminated is its heavy,more expensive and can crack under its own weight when installed in large units.

Thanks again welsh brickie, very helpful to understand the difference. I wrongly assumed laminated would be best.

Cheers, DD